Patent GB-868827-A (GB)
Title: Variable speed transmission
IPC: F16H15/40
Filed: 1957-09-06
Abstract: 868,827. Variable-speed friction gear. ROUVEROL, W. S. Sept. 6, 1957 [Sept. 24, 1956], No. 28148/57. Class 80 (2). A steplessly variable speed gear comprises a large number of balls 14 mounted in a rotatable cage 10 which balls roll without slipping between opposed discs 3, 4. Either the two discs 3, 4 or one of the discs and the cage may be the driving and driven members and either the cage or both discs are movable to effect ratio shift. The traction pressure between the discs is supplied by spring as torque responsive means. In Fig. 2 input and output discs 3, 4 are drivingly connected by balls 14 grouped in a common cage 10 carried in a ball bearing in a plate 5 traversed by a screw 17 in a direction XX containing the disc axes to vary the ratio. The cage 10 comprises recessed plates secured together and may (Fig. 6, not shown) include smaller balls between and contacting the main balls. In Fig. 4 the ball-cage 40 is the driving member and comprises an apertured disc driven frictionally by a roller 43 on an input shaft 44. The upper disc 41 is the driven member and drives an output shaft 48 through a bevel gear 46, whilst the lower disc 42 is an idler, or may provide an additional power take-off. The cage 40 rotates on a fixed axis determined by the driving roller 43 and two spaced additional idler rollers contacting the periphery of the cage. To vary the ratio the discs 41, 42 are simultaneously traversed in opposite directions parallel to the output shaft 48, for which purpose they are freely mounted in peripheral ball bearings 53 in rectangular plates 51, 52 which, by a manual rack-and-pinion gear, are oppositely moved along grooves 55, 56 in the side walls of the casing, the output bevel wheel 46 sliding with the upper disc on splines on the output shaft 48. Traction pressure is applied to the discs by a spring 31 acting through thrust bearings 33, 34 of the tilting pad type. In Figs. 8 and 9 (not shown) input and output shafts each carry alternately two discs having three interposed ball cages carried by a common shiftable support. Pressure application.-Various torque responsive means for applying traction pressure to the discs are described. In Fig. 10 (not shown), for the Fig. 2 arrangement, forces are generated acting axially of the disc shafts and responsive to the respective input and output torques to provide a resultant acting always through the cage centre. In Fig. 11 a friction disc 86 is connected to its driving shaft 80 by a friction bevel gear the pinion 82 of which is screw threaded on a bush 81 which itself has an oppositely handed screwthreaded mounting on the shaft 80. Shoulders limit relative axial movement and torque transmitted from the shaft to the disc in either direction of rotation applies an axial inward thrust to the bevel pinion 82 and hence an upward thrust to the friction disc 86. A spring 127 provides initial loading. In Fig. 12 (not shown) the shaft is parallel to the axis of the disc and drives it through helical toothed gearing providing torque-responsive axial loading for one direction of rotation. In Fig. 13 a shaft 100 is drivingly connected to its friction disc 103 through a bevel differential gear, the reaction of which is taken by a spur pinion 105 mounted on a ball thread on a shaft 106 carrying a roller 107 through which it exerts a torque-responsive thrust on the disc. A spring 128 provides initial loading. In Fig. 14 (not shown) the friction disc carries a spur wheel meshing a pinion mounted on a parallel driving shaft through a screw thread which applies axial force to the pinion and thence through a thrust bearing to the disc itself. Ratio shift.-The shift control of Fig. 15 (not shown) differs from Fig. 2 in that the cage carrying plate 5 is pivoted to the adjusting nut 16 about an axis parallel to that of the discs to permit movement of the cage centre towards and away from the line joining the disc axes. The initial shift movement moves the cage centre off this line after which the drive causes it to return to the line in a new equilibrium position. In Fig. 16 (not shown) the cage carrier is linked in a frame plate traversed rectilinearly by the screw, the cage centre thus having lateral freedom in a predetermined curve. In Figs. 18 and 19 (not shown) the cage carrier has an equivalent slotted mounting in the frame.